The present invention relates to VEGF-receptor antagonists inhibiting VEGF, which corresponds to specific growth factors of vascular endothelial cells, from binding to receptors.
The present application is based on patent applications in Japan (Japanese Patent Application No. Hei 11-188271 and Japanese Patent Application No. Hei 11-188272), the disclosure of which is incorporated herein by reference as a part of the present description.
VEGF (vascular endothelial growth factor) is a growth factor exhibiting extremely high specificity to vascular endothelial cells. VEGF and the receptors thereof play main roles in physiologic angiogenesis such as placentation or development. As VEGF receptors, Flt-1 (fms-like tyrosine kinase) and KDR (kinase insert domain containing receptor) have been reported (Advances in Cancer Research, vol. 67, pp. 281-316, 1995).
It is suggested that VEGF and the receptors thereof play main roles not only in physiologic angiogenesis but also in pathologic angiogenesis observed in diseases such as diabetic retinopathy, chronic rheumatism, and solid tumors (Advances in Cancer Research, vol. 67, pp. 281-316, 1995), and are involved in progress of these diseases. In addition, it is known that VEGF and the receptors thereof are involved not only in angiogenesis but also in vascular hyperpermeability. It is suggested that vascular hyperpermeability due to VEGF is involved in pathologic symptoms such as carcinomatous ascites retention or cerebral edema upon ischemia reperfusion injury (J. Clin. Invest., vol. 104, pp. 1613-1620, 1999).
Therefore, it is believed that substances which inhibit binding between VEGF and the receptors thereof are considered to be useful in treatment of various diseases in which pathologic angiogenesis due to VEGF is involved, and amelioration of pathologic symptoms in which vascular hyperpermeability due to VEGF is involved.
An objective of the present invention is to provide compounds for use as a VEGF-receptor antagonist for treating diseases in which angiogenesis induced by VEGF is involved, and for ameliorating pathologic symptoms in which vascular hyperpermeability induced by VEGF is involved.
The compounds according to the present invention correspond to aminobenzoic acid derivatives represented by Formula (1) as follows: 
{in Formula (1), R1 represents a hydrogen atom or a C1-6alkyl group;
R2 represents a hydrogen atom, a C1-6alkyl group, a C3-8 cycloalkyl C1-3alkyl group, a phenyl C1-3alkyl group, a group represented by CH2CO2R5 (wherein R5 represents a hydrogen atom or a C1-6alkyl group), or a group represented by CH2CON(R6)R7 (wherein R6 and R7 independently represent a hydrogen atom or a C1-6alkyl group);
R3 represents a C8-25alkyl group, a group represented by (CH2)pCO2R11 (wherein p is an integer of 1 to 20, and R11 represents a hydrogen atom or a C1-6alkyl group), or a group represented by (CH2)3CONHCH(R12) CONHR13 (wherein R12 represents a hydrogen atom or a group represented by CH2CO2R14 group (wherein R14 represents a hydrogen atom or a C1-6alkyl group), and R13 represents a C1-20alkyl group);
R4 represents a hydrogen atom or a group represented by OR9 or CO2R10 (wherein R9 and R10 independently represent a hydrogen atom or a C1-6alkyl group),
A represents a group represented by S(O)qR15 (wherein q is 0, 1, or 2, R15 represents a C1-6alkyl group, a phenyl C1-3 alkyl group, or a group represented by (CH2)mOR16 (wherein m is 2 or 3, and R16 represents a hydrogen atom or a methoxymethyl group)), a group represented by Formula (2) as follows: 
(in the formula, R17 represents a hydrogen atom or a group represented by CO2R19, CH2CO2R20, CH2CH2CO2R21, or CHxe2x95x90CHCO2R22 (wherein R19, R20, R21, and R22 independently represent a hydrogen atom or a C1-6alkyl group), R18 represents a hydrogen atom or a group represented by CO2R23 (wherein R23 represents a hydrogen atom or a C1-6alkyl group), Yxe2x80x2 represents O, S, or NR24 (wherein R24 represents a hydrogen atom or a C1-6alkyl group), and Z represents CH or N), or a group represented by Formula (3) as follows: 
(in the formula, R25 represents a hydrogen atom or a group represented by CO2R26 (wherein R26 represents a hydrogen atom or a C1-6alkyl group));
X represents O, a single bond, or a group represented by NR27 (wherein R27 represents a hydrogen atom or a t-butoxycarbonyl group);
Y represents O, CONH, NHCO, or a group represented by NR28 (wherein R28 represents a hydrogen atom or a t-butoxycarbonyl group, with the proviso that when Y represents NHCO, A is not represented by Formula (2) described above); and
n is an integer of 0 to 15}
or pharmaceutically acceptable salt of the same.
In the present invention, the term xe2x80x9cC1-6alkyl groupxe2x80x9d means a straight-chain or branched-chain alkyl group having 1 to 6 carbon atoms. As examples thereof, mention may be made of, for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a t-butyl group, a pentyl group, an isopentyl group, a 1-ethylpropyl group, a hexyl group, an isohexyl group, a 1-ethylbutyl group, and the like. The term xe2x80x9cC3-8cycloalkyl C1-3alkyl groupxe2x80x9d means a straight-chain or branched-chain alkyl group having 1 to 3 carbon atoms, substituted with a cycloalkyl group having 3 to 8 carbon atoms. As examples thereof, mention may be made of, for example, a cyclopropylmethyl group, a cyclobutylmethyl group, a cyclopentylmethyl group, and the like.
The term xe2x80x9cC8-25alkyl groupxe2x80x9d means a straight-chain or branched-chain alkyl group having 8 to 25 carbon atoms. As examples thereof, mention may be made of an octyl group, a 7-methyloctyl group, a 7,7-dimethyloctyl group, an octadecyl group, a 17-methyloctadecyl group, a 17,17-dimethyloctadecyl group, a pentacosyl group, a 23-methyltetracosyl group, a 22,22-dimethyltricosyl group, and the like.
The term xe2x80x9cC1-20alkyl groupxe2x80x9d means a straight-chain or branched-chain alkyl group having 1 to 20 carbon atoms. As examples thereof, mention may be made of, for example, a methyl group, an ethyl group, a decyl group, a 9-methyldecyl group, a 9,9-dimethyldecyl group, an icosyl group, and the like.
The term xe2x80x9cphenyl C1-3alkyl groupxe2x80x9d means a straight-chain or branched-chain alkyl group having 1 to 3 carbon atoms, substituted with a phenyl group. As examples thereof, mention may be made of, for example, a benzyl group, a 2-phenylethyl group, a 3-phenylpropyl group, and the like.
In addition, as examples of the pharmaceutically acceptable salt in the present invention, mention may be made of, for example, a salt with an inorganic acid such as sulfuric acid, hydrochloric acid, or phosphoric acid, or the like; a salt with an organic acid such as acetic acid, oxalic acid, lactic acid, tartaric acid, fumaric acid, maleic acid, methanesulfonic acid, benzenesulfonic acid, or the like; a salt with an amine such as trimethylamine, methylamine, or the like; a salt with a metal ion such as sodium ion, potassium ion, calcium ion, or the like; and the like.
In addition, some of the compounds according to the present invention exhibit crystal polymorphism. The present invention includes any crystal forms thereof.
In Formula (1), it is preferable that A represent a group represented by S(O)qR15 (wherein q and R15 have the same meanings as described above) or a group represented by Formula (5) as follows: 
(in the formula, R17 R18, and Yxe2x80x2 have the same meanings as described above), and it is more preferable that A represent a group represented by SR15 (wherein R15 has the same meaning as described above) or a group represented by Formula (5) wherein R17 represents CO2R19 (wherein R19 has the same meaning as described above) and R18 represents a hydrogen atom. In addition, it is most preferable that A represent a group represented by SR15 (wherein R15 represents a C1-6alkyl group) or a group represented by Formula (5) wherein R17 represents CO2H and R18 represents a hydrogen atom.
In addition, in Formula (1), R2 preferably presents a hydrogen atom or a C1-6alkyl group.
In Formula (1), R3 preferably represents a straight-chain or branched-chain alkyl group having 8 to 25 carbon atoms, and more preferably represents an alkyl group having 14 to 22 carbon atoms, and most preferably represents an alkyl group having 18 carbon atoms.
In Formula (1), it is preferable that R4 represents a hydrogen atom.
In Formula (1), it is preferable that a CO2R1 group is located at the position as shown in Formula (4) as follows: 
and it is preferable that A in Formula (4) is located at the position as shown in Formula (6) as follows: 
In addition, it is preferable that X represents O or a single bond, and it is more preferable that X represents a single bond.
It is preferable that Y represents O. It is preferable that n is 1 or 2.
Therefore, the preferable compounds in the present invention are selected from those having combinations of the preferable substituents described above.
The compounds of the present invention can be produced according to the reactions described below.
1) Case in Which a Represents a Group Represented by S(O)qR15 
The symbols in the formula have the same meanings as described above. Axe2x80x2 represents S(O)qR15; halo means a halogen atom; R represents R2 excluding a hydrogen atom; Rxe2x80x2 represents a t-butyl group, a p-methoxybenzyl group, or a diphenylmethyl group; and Rxe2x80x3 represents a lower alkyl group. 
A compound represented by Formula (9) according to the present invention is prepared by condensation between a compound of Formula (7) and a carboxylic acid compound of Formula (8). As the condensing agent, there can be employed the condensing agents commonly used when amides are produced by amines and carboxylic acids, such as 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride and 1-hydroxybenzotriazole. As the solvent, inert solvents such as N,N-dimethylformamide and the like can be employed. The compound of the present invention of Formula (9) can be also produced by converting the carboxylic acid of Formula (8) into an acid halide or a mixed anhydride according to a common method, followed by a reaction with the compound of Formula (7) in the presence of a base. As the base, pyridine, triethylamine, or the like may be employed. As examples of the solvent, mention may be made of inert solvents such as methylene chloride and the like.
A compound of Formula (10) according to the present invention in which the nitrogen atom of the amide group is modified (by R) can be produced by carrying out a substitution of the hydrogen atom of the amide group in the compound of Formula (9) in the presence of a strong base. In this reaction, as examples of the base, mention may be made of sodium hydride, potassium hydride, calcium hydride, and the like. As the solvent, inert solvents such as N,N-dimethylformamide and the like can be employed.
Among these compounds of Formula (10), a compound having CH2CO2Rxe2x80x2 as R can be converted into a carboxylic acid compound of Formula (11), by a reaction in the presence of a strong acid such as trifluoroacetic acid or the like in an inert solvent such as methylene chloride or the like.
The carboxylic acid compound of Formula (11) can react with an amine of Formula (12) in the presence of a condensing agent to yield an amide compound of Formula (13). As the condensing agent, there can be employed the condensing agents commonly used when amides are produced by amines and carboxylic acids, such as 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride and 1-hydroxybenzotriazole. As the solvent, inert solvents such as N,N-dimethylformamide and the like can be employed.
A compound of Formula (14) can be produced by reacting a compound of Formula (1) in which R1 represents t-Bu and X represents N(CO2Bu-t) in the presence of a strong acid such as trifluoroacetic acid in an inert solvent such as methylene chloride.
A compound of Formula (15) can be produced by reacting a compound of Formula (1) in which R1 represents t-Bu and X represents N(CO2Bu-t) in the presence of a strong acid such as trifluoroacetic acid in an inert solvent such as methylene chloride.
A compound of Formula (16) can be produced by reacting a compound of Formula (1) in which Axe2x80x2 represents S(CH2)mOCH2OMe in the presence of an acid such as hydrochloric acid, sulfuric acid, acetic acid, trifluoroacetic acid, or the like in a solvent mixture of a lower alcohol such as methanol and a polar solvent such as tetrahydrofuran.
The compounds of the present invention in which R1 represents an alkyl group, R4 represents an alkoxycarbonyl group, or R3 represents an alkoxycarbonylalkyl group can yield the compounds of the present invention in which R1 represents a hydrogen atom, R4 represents a carboxyl group, or R3 represents a carboxyalkyl group, respectively, according to the common methods of hydrolysis in which an ester group is subjected to a hydrolysis.
In addition, the compounds of the present invention in which Axe2x80x2 represents SR15 can yield the compounds of the present invention in which Axe2x80x2 represents SOR15 or SO2R15, by an oxidation with an oxidant such as m-chloroperoxybenzoic acid or the like in an inert solvent such as methylene chloride or the like.
2) Case in Which A Represents a Group Represented by Formula (2) or Formula (3)
As an example, a case in which A in Formula (1) described above represents a group represented by Formula (2) is described. The symbols in the formulae have the same meanings as described above, and xe2x80x9chaloxe2x80x9d represents a halogen atom and R represents R2 excluding a hydrogen atom. 
A compound of Formula (17) and a nitro compound of Formula (18) are stirred in the presence of a base and in the presence or absence of a catalytic amount of copper powders in an appropriate solvent at temperatures of 0xc2x0 C. to 150xc2x0 C., to yield a compound of Formula (19). As the base, there can be employed inorganic bases such as potassium carbonate, sodium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, cesium carbonate, sodium hydride, potassium hydride, and the like; organic bases such as triethylamine, diisopropylethylamine, pyridine, and the like; or the like. As the solvent, an inert solvent such as N,N-dimethylformamide or the like can be employed.
According to need, the compound of Formula (19) is stirred with a lower alkyl halide in the presence of a base in an appropriate solvent at temperatures of 0xc2x0 C. to 100xc2x0 C. to yield the compound of Formula (19) in which R17 represents a hydrogen atom or a group including an alkoxycarbonyl group, R18 represents a hydrogen atom or an alkoxycarbonyl group, and R1 represents an alkyl group. As the base, potassium carbonate, sodium carbonate, sodium hydrogencarbonate, potassium hydrogencarbonate, cesium carbonate, or the like can be employed. As the solvent, an inert solvent such as N,N-dimethylformamide or the like can be employed.
Subsequently, the nitro group in the compound of Formula (19) which does not include a carboxyl group is reduced to an amino group to yield a compound of Formula (20). As examples of the reduction method, mention may be made of a reduction using a metal such as iron or tin or a metal salt in the presence of an acid such as acetic acid or hydrochloric acid and ammonium chloride; a catalytic hydrogenation using a catalyst such as palladium/carbon, Raney nickel, platinum oxide, or the like; a reduction using ammonium formate in the presence of a palladium/carbon catalyst; or the like. As examples of the solvent, mention may be made of inert solvents such as methanol, ethanol, isopropyl alcohol, and the like.
The compound of Formula (20) obtained herein is condensed with a carboxylic acid of Formula (21) to yield a compound of Formula (22) of the present invention. As the condensing agent, there can be employed the condensing agents commonly used when amides are produced by amines and carboxylic acids, such as 1-(3-(dimethylamino)propyl)-3-ethylcarbodiimide hydrochloride and 1-hydroxybenzotriazole. As the solvent, inert solvents such as N,N-dimethylformamide and the like can be employed. Alternatively, the compound of Formula (22) can be prepared by converting the carboxylic acid of Formula (21) into an acid halide or a mixed anhydride according to a common method, followed by a reaction with the compound of Formula (20) in the presence of a base. As the base, pyridine, triethylamine, or the like can be employed. As the solvent, an inert solvent such as methylene chloride or the like may be mentioned.
Alkylation of the compound of Formula (22) is carried out in the presence of a strong base, to yield a compound (23) of the present invention in which the nitrogen atom of the amide is alkylated. In the case of the compounds of Formula (22) in which Yxe2x80x2 represents NH, the compounds of the present invention in which R2 represents an alkyl group, and Yxe2x80x2 represents an N-alkyl group can be yielded. As examples of the base herein, mention may be made of sodium hydride, potassium hydride, calcium hydride, and the like. As the solvent, an inert solvent such as N,N-dimethylformamide or the like can be employed.
The compounds of Formula (22) and Formula (23) in which R1 represents an alkyl group, R17 represents a hydrogen atom or a group including an alkoxycarbonyl group, and R18 represents a hydrogen atom or an alkoxycarbonyl group can respectively yield the compounds of the present invention in which R1 represents a hydrogen atom, R17 represents a hydrogen atom or a group including a carboxyl group, and R18 represents a hydrogen atom or a carboxyl group, according to the common methods of hydrolysis in which an ester group is subjected to a hydrolysis.
The compounds of the present invention in which A of Formula (1) described above represents a group represented by Formula (3) can be prepared according to the same operations as described in the preparation methods for the compounds in which Y in the groups represented by Formula (2) represents O.
The compounds represented by Formula (1) or pharmaceutically acceptable salts of the same are employed as the VEGF-receptor antagonists described above, and in particular, as therapeutic agents of the diseases in which VEGF is involved, and are employed in manufacture thereof. The VEGF-receptor antagonists of the present invention inhibit proliferation of VEGF-dependent vascular endothelial cells by inhibiting binding between the ligands (VEGF) and the VEGF receptors to inhibit angiogenesis, as well as inhibit vascular hyperpermeability due to VEGF.
Herein, as examples of diseases and pathologic symptoms in which VEGF is involved, mention may be made of diabetic retinopathy and other retinopathies, chronic rheumatism, solid tumors, ischemia-reperfusion-injury related cerebral edema and damage, psoriasis, atherosclerosis, retrolental fibroplasia, neovascular glaucoma, age-related macular degeneration, thyroid gland hyperplasia (including Graves"" disease), chronic inflammation, pneumonia, nephrotic syndrome, tumor immune hypofunction, ascites retention, pericardial effusion (those relating to pericarditis, and the like), retention of pleural effusion, and the like.
Among these, in particular, in the diseases described below, ameliorations in pathologies by inhibition of VEGF have been reported.
(1) Diabetic Retinopathy and Other Retinopathies
Diabetic retinopathy refers to diseases in which various lesions form in the retina or vitreous body due to abnormalities in retinal blood vessels, caused by exposure under hyperglycaemic conditions for a long period of time. It is known that according to progress of the disease, abnormal angiogenesis and bleeding in the eyeball lead to blindness. In addition, it is reported that there is a positive correlation relationship between increasing in VEGF level in the eyeball and abnormal angiogenesis in the eyeball (New Engl. J. Med., vol. 331, pp. 1480-1487, 1994). In addition, it is reported that in a retinopathy model of a monkey, by intraocular administration of an anti-VEGF neutralizing monoclonal antibody, VEGF activities are inhibited to result in inhibition of angiogenesis (Arch. Opthalmol., vol. 114, pp. 66-71, 1996), and that in a retinopathy model of a mouse, by administration of an inhibitor of VEGF signal transduction, retinal angiogenesis is inhibited (Am. J. Pathol., vol. 156, pp. 697-707, 2000). As described above, it may be understood that VEGF-receptor antagonists are effective on diabetic retinopathy and other retinopathies.
(2) Chronic Rheumatism
It is reported that the serum VEGF values of patients suffering from chronic rheumatism are significantly higher as compared to those of healthy persons, and in nidal regions, production of VEGF is increased (J. Immunol., vol. 152, pp. 4149-4156, 1994), and it is suggested that VEGF is greatly involved in formation of diseases. In addition, in a collagen arthritis model of mouse, ameliorating actions for diseases by administration of an anti-VEGF antiserum are reported (J. Immunol., vol. 164, pp. 5922-5927, 2000).
(3) Solid Tumors
It is believed that VEGF plays important roles in angiogenesis in malignant tumors (Biochem. Biophys. Res. Commun., vol. 161, pp. 851-858, 1989).
It is known that production of VEGF is increased in cerebral tumors such as gliomas, malignant lymphomas, pituitary adenomas, meningiomas, and the like, various solid malignant tumors such as melanomas, colon cancers, ovarian cancers, pancreatic cancers, esophageal cancers, rhabdomyosarcomas, leiomyosarcomas, Kaposi""s sarcoma, lung cancers, and the like (Nature, vol. 362, pp. 841-844, 1993; Biochem. Biophys. Res. Commun., vol. 183, pp. 1167-1174, 1992). It is believed that VEGF secreted from tumor cells causes proliferation of vascular endothelial cells by binding to tyrosine-kinase-type receptors which are specifically present in vascular endothelial cells, and are involved in proliferation or metastasis of tumors due to induction of tumor angiogenesis (Oncogene, vol. 5, pp. 519-524, 1990; Science, vol. 255, pp. 989-991, 1992).
It is reported that tumor proliferation can be inhibited by administration of an anti-VEGF monoclonal antibody in an implantation model in the nude mouse of glioblastoma, rhabdomyosarcoma, and leiomyosarcoma (Nature, vol. 362, pp. 841-844, 1993), and it is suggested that VEGF-receptor antagonists exhibit anti-tumor effects on various solid tumors.
(4) Ischemia-reperfusion-injury Related Cerebral Edema and Damage
It is believed that VEGF is involved in the etiology of edema due to vascular hyperpermeability effects thereof, and it is reported that in a cerebral ischemia model in the mouse, cerebral edema and damage are inhibited by administration of fused proteins of mouse VEGF-receptor protein (mFlt(1-3)) and IgG (J. Clin. Invest., vol. 104, pp. 1613-1620, 1999).
When the compounds of the present invention are employed as VEGF-receptor antagonists or therapeutic agents for the diseases in which VEGF is involved, they can be administered orally or parenterally.
The dosage forms of the same are tablets, capsules, granules, abstracts, powders, troches, ointments, creams, emulsions, suspensions, suppositories, injections, or the like, each of which may be produced according to the conventional formulation methods (for example, methods defined in the 12th revised edition of the Japanese Pharmacopeia). These dosage forms may be appropriately selected depending on the conditions and ages of the patients, as well as the purpose of the treatment. Upon manufacturing preparations in various formulations, conventional excipients (for example, crystalline cellulose, starch, lactose, mannitol, or the like), binders (for example, hydroxypropylcellulose, polyvinylpyrrolidone, or the like), lubricants (for example, magnesium stearate, talc, or the like), disintegrants (for example, carboxymethylcellulose calcium, or the like), and the like, may be employed.
The doses of the compounds according to the present invention are in the range of 1 to 2000 mg per day in a single dose or divided into several doses, in the case of an adult human subject to be treated. The doses may vary appropriately depending on the age, weight, and condition of each individual patient.